Top medical experts studying the spread of Ebola say the public should expect more cases to emerge in the United States by year’s end as infected people arrive here from West Africa, including American doctors and nurses returning from the hot zone and people fleeing from the deadly disease.

All travelers who come into the U.S. from three Ebola-stricken West African nations will now be monitored for three weeks, the latest step by federal officials to keep the disease from spreading into the country.